Television lamp and apparatus



Aug. 10, 1937. w, McKAY 2,089,806

TELEVISION LAMP AND APPARATUS Filed Aug. 11, 1932 2 Sheets-Sheet l 20 J 29/ Z Z l L AL INVENTOR [0/10 14/ Mc/lay BY A ATTORNEY 10, 1937. J. w. MCKAY 2,089,806

TELEVISION LAMP AND APPARATUS Filed Aug. 11, 1932 2 Sheets-Sheet 2 INVENTOR Jbhn W Mc Ka BY ATTORNEY Patented Aug. 10, 1937 I UNITED STATES PATENT OFFICE 2,089,806 'rnnnvrslon LAMP AND APPARATUS John W. McKay, Brooklyn, N. Y., aslignor, by

meme assignments, to National Television Cornotation, Delaware Wilmington, DeL, a corporation of This invention relates to electric discharge lamps and particularly to lamps for producing a line of light.

One of the objects of the invention is to produce an electric discharge lamp having a bright intense illumination which follows a predetermined line.

Another object of the invention is to produce a discharge lamp in which the line of light has an intense bluish white color.

A still further object of the invention is to produce a discharge lamp having an intense illumination which may be modulated without danger of the discharge ceasing entirely due to 16 the time element in the operating impulses.

Other objects of the invention and objects relating particularly to the method of constructing and assembling the various parts of the lamp will be apparent as the description of the invention proceeds.

One embodiment of the invention has been iilustrated in the accompanying drawings in which:

Fig. 1 is a side elevational view partly in section of a lamp embodying the invention;

Fig. 2 is a sectional plan view through the cathode of the lamp and taken on the line 2-2 of Fig. 1; and

Fig. 3 is a sectional side elevational view of a television receiving set using the discharge lamp.

Referring now more specifically to the drawings, the lamp is shown in Fig. 1 as comprising a pair of transparent envelopes l0 and II joined by a relatively long, straight, transparent tube I2 which is fused to each of the envelopes and forms a connecting duct between them. Both of the envelopes l0 and II may be formed of glass or other transparent material, such as quartz, which is suitable for electric lamp use, and may be about the size of a ten watt electric light bulb having a diameter of 1% inches. The tube l2 may be formed of the same material as the envelopes. The envelopes Ill and II are joined at their tips or rounded ends so that the press l3 of the envelope l0 is adjacent the top oi. the envelope while the press ll of the envelope H is at the bottom thereof. A support rod I5 is sealed in the press l3 of the upper envelope and to the end thereof is connected a metal cup it formed of any suitable thin metal such as nickel, Swedish iron, tantalum, tungsten, or the like, by means of a short connector H, which is welded to the cup and to the end of the rod I5. In order to prevent discharge from iorming on the support rod ll adjacent the press and possibly overheating the press, I provide a disc l8, which may be formed of mica or other suitable insulating materlal, and may be mounted upon the connector I! and held against the cup l6 by the support rod II. The disc I8 is preferably large enough to almost touch the walls of the bulb.

The cathode I9 is positioned in the lower bulb or envelope H and may comprise a strip of metal gauze 20 rolled around a. central support rod 2| in the form of a spiral. This cathode may be made of metal similar to that mentioned for the anode, but nickel, however, is preferred. In one instance where good results were obtained, I formed the cathode out of a strip of wire mesh one inch wide and 9% inches long, rolling it up as indicated and securing it by welding to the support rod 2|. The support rod 2| may extend slightly below the rolled cathode l9 and a disc 22 of mica or other insulating material similar to the disc l8 described in connection with the anode may be slipped over the end of the rod 2| and then the rod 2| welded to the support rod 23 which is sealed in the press ll. Lead-in wires 24 and 25 may be connected respectively to the support rods It at the top of the bulb f and 23 at. the bottom so as to form the external electrical connectors for the lamp.

The connecting tube l2 may be made any desired length depending on the use intended for the lamp. In one instance where successful operation was had with a television receiving apparatus, I made the tube I2 ten inches long while its diameter was approximately 4''.

The lamp may be filled with an ionizable gas,

as for instance one of the monatomic gases such as neon, argon, helium, krypton, and xenon, although metal vapors may also be added to increase the conductivity of the gas or to produce color effects. With a lamp having the dimensions referred to above, I prefer to use 10 mm. of neon gas at the same time including a small drop Ila of mercury so that when the temperature of the gas rises in use the mercury will vaporize and the mixture of neon gas and mercury vapor will fill the entire envelope. In introducing the gas to the lamp the occluded gases should be driven off from the metal parts by either baking the bulb while the exhaust pump is attached thereto, in a manner well known in the art, or raising the temperature of the anode and cathode independently by external bombardment,

When the lamp has been properly exhausted and the neon gas and mercury have been added, the lamp may be sealed off and is ready for use.

A lamp so formed when connected in a circuit 5 and supplied with a current in the neighborhood of 100 milli-amperes at a pressure of from 600 to 1500 volts will produce a bluish white intense light through the tube l2 which is uniform in intensity throughout the length of the tube. I have found it advisable, however, to provide some means to give the lamp an initial impulse at a very much higher voltage so as to insure the starting thereof. This may be done in a manner to be hereinafter described.

When the lamp is cold and the discharge first appears in it, most of the mercury is in a liquid form and the current therefore flows through the neon gas which causes a red light. As the lamp warms up, the mercury begins to vaporize, especially near the cathode, with the result that the light begins to change adjacent the cathode to a bluish white which gradually creeps along the tube I2 eliminating the red until the entire tube is filled with the bluish white discharge. As this phenomenon takes place there is a distinct line between the bright red color of the neon discharge and the bluish white. color of the mixture of neon and mercury vapor, and. several seconds may elapse before the lamp has reached its operating color of bluish white and the red is completely eliminated.

I have found that during the operation of the lamp if the mercury or a part of it is suddenly caused to be condensed on the walls of the lamp, the reddish color will again appear at that point. Due to the fact that the temperature of the cathode is considerably higher than that of the anode, there appears to be little danger of the mercury condensing in the bulb H, but in the 40 bulb II where the anode has normally a lower temperature there may be danger of the mercury condensing if the bulb is subjected to drafts or otherwise suddenly cooled. This gives rise not only to the removal of the mercury vapor from 45 the mixture of gas but a difference in pressure which perhaps may affect the discharge. Whether the condition arises from the temperature alone or from variation of temperature is not quite clear, but I have found that if the 60 bulb l containing the anode is protected in some manner against draft or other cooling influences, the bluish white light of the lamp 'is constant and no red appears while it is in operation. One way of thus protecting the anode bulb 56 II is by providing a cover Illa of felt, asbestos, or other suitable material which may be made with a restricted opening "3b to fit over the neck of the bulb and a suitable draw string lllc to draw the covering closely against the rounded portion of the bulb and against the end 01' the tube l2. However, the apparatus may be arranged so that a shadow box Ila, (Fig. 3), is adapted to fit closely around the bulb l0 so that it is protected from drafts and the cover Illa may then be 5 omitted.

While the lamp is shown with the cathode at the lower end and the anode above, it is not necessary to operate it in thisposition as it may 70 be turned in any position without apparent effect on the operation thereof.

In using a modulated light, as for instance with television apparatus where incoming signal impulses cause the lamp to flicker in accordance 75 therewith, some difficulty has been experienced in causing the discharge to start again after a relatively long dark impulse has come over the circuit. The use of the mercury in the present lamp appears to maintain the ionization throughout the length of the tube between the anode and cathode and to therefore permit the discharge to start again instantaneously after a long dark period. Whatever the theory of operation the lamp as described above with the voltage and current mentioned will receive very heavy modulation without being extinguished.

' In Fig. 3 the lamp is shown used in connection with a certain type of television receiving apparatus in which a drum 26 is formed similarly to that described in the patent to Gardner No. 1,753,697. This drum comprises a plurality of plates 21 arranged in a stack on a shaft 28 which passes through a hole in the center of each plate. A nut 29 threaded on the shaft may urge the plates against a shoulder 30 on the shaft, a heavy plate or bar 29a at the top being interposed between the plates, which may be relatively thin, and the nut. and a washer 29b between the bar and nut may be provided as indicated. Similarly a bar 30a and washer 30b may be interposed between the shoulder 30 and the lowermost plate. By screwing the nut 29 down tightly the plates may be rigidly held in position.

The plates 21 may be rectangular in shape and may each be provided with one long reflecting edge 3i substantially parallel to the shaft 28. The plates are arranged on the shaft 28 so that the surfaces 3| form a spiral around the drum uniformly withequal angles so that with one revolution of the drum all of the plates will have passed in regular succession in front of the observer. In accordance with the said application, the opposite edges 32 of the plates are formed at an angle so that light intercepted thereby will be reflected away fromthe observer and this may also be true with the end edges 33 and 34. A motor 3! drives the drum at a constant speed in synchrony with the transmitting apparatus. Where the transmitting apparatus and receiving apparatus are run from the same power circuit an ordinary synchronous motor will accomplish this result but where the power circuits are different it will be necessary to provide some means (not shown) to synchronize the motor 35 with the motor of the sending apparatus.

The lamp described above may be positioned a short distance away from the drum 26 and may have its terminals 24 and 25 connected by means of wires 36 and 31 respectively to the output of a radio receiving set 38, which picks up the incoming television signal. The lead 24 and wire 38 are, of course, connected to the positive output terminal of the set. In order to start the lamp, I have found it desirable to provide a high tension coil 38 having a secondary winding 40 connected across the terminals of the lamp by means of wires 4| and 42 which may be connected to the wires 31 and 36 respectively. The coil has a primary winding 43 connected to a battery 44 through an operating switch 45 and an interrupter 45a. In starting the lamp the switch 46 is momentarily closed whereupon a discharge of high tension current will pass through the lamp thus ionizing the gas in the tube l2 and when the switch 45 is opened again the lamp continues to operate on the output of the radio set 33. A suitable spark gap 46 may be provided in the secondary circuit, forming a break, for

erating current from flowing through the secondary winding.

From the above it will be seen that I have provided a lamp which is suitable for television ap- 5 paratus in that it produces an intense light which may be readily modulated without being extinguished due to heavy signals. The lamp is easily and inexpensively constructed and will opcrate withgreat uniformity. While the lamp has been especially described in connection with a --eer.tain type of television apparatus, it is evident that it may be used with other types or under any conditions where a discharge light is desiredor where modulated light is required. Also while the tube l2 has been shown as a "straight tube, it is obvious that it may be bent in any desired configuration, or twisted or coiled up, so thatietters or other insignia may be made with it without interfering in any way with its operation.

Many-other modifications of the invention may be resorted to without departing from the spirit thereof, and I do not, therefore, desire to limit myself to what has been shown and described ex-- :ipt as such iimitations occur in the appended What I desire to claim is: l 1. A lamp for producing modulated light comi ii'ising a cathode and an anode spaced apart. 80 said cathode having a suri'ace-to-volume ratio of several hundred, an ionizable gas surrounding said cathode and anode, a restricted path for said gas between said cathode and anode, the surface area of said cathode being several hun- 35 dr'ed times the cross-sectional area of said path, and heat insulating means to maintain thecondition of said gas constant in the neighborhood ofsaid anode.

A lamp for producing modulated light com- 4 prising an anode and cathode spaced apart, said cathode having a surface-to-volume ratio of several hundred, van ionizable gas containing a metal vapor surrounding said anode and cathode, a restricted path between said anode and cath- 45 ode. the surface area of said cathode being several hundred times the cross-sectional area of said path, and heat insulating means to maintain constant the condition of the gas in the neighborhood of said anode. 5g 3. A lamp for producing modulated light comprising an anode and a cathode spaced apart, said cathode having a surface-to-volume ratio of several hundred, a gas containing mercury vapor: surrounding said anode and cathode, a 55 restricted path for said gas between said anode and cathode, the surface area of said cathode being several hundred times the cross-sectional area .of said path, and heat insulating means to mai ntain constant the condition of said gas adjacent said anode.

4. A lamp for producing modulated light comprising-an anode and a cathode spaced apart, said cathode having a surface-to-volume ratio ofseveral hundred, an ionizable gas containing new and mercury surrounding said anode and cathode, a restricted path between said anode and cathode, the surface area of said cathode being several hundred times the cross-sectional area of said path, and heat insulating means to 70 maintain constant the condition of said gas in the neighborhood of said anode.

5. A lamp for producing modulated light comprising an anode and a cathode spaced apart, said cathode having a surface-to-volume ratio of sev- 75 eral hundred, a gas consisting of approximately 10 mm. of neon and a trace of mercury vapor surrounding said anode and cathode, a restricted path for said gas between said anode and cathode, the surface area of said cathode being several hundred times the cross-sectional area of said 5 Path, and heat insulating means to maintain constant the condition of the gas in the neighborhood of said anode.

6. A television lamp comprising a pair of spaced apart electrodes, one of said electrodes having 10 many times more surface than the other, an ionizable gas surrounding said electrodes, and heat insulating means to maintain constant the condition of the gas in the neighborhood of the smaller electrode. 15

7. A television lamp comprising a pair of spaced apart electrodes, one of said electrodes having more surface than the other, an ionizable gas surrounding said electrodes, said gas comprising a mixture of neon and of metal vapor, and heat 20 insulating means to maintain the condition of the gas constant in the neighborhood of the smaller electrode.

8. A television lamp comprising a pair of spaced apart electrodes, one of which is larger 26 than the other, an ionizable gas containing mercury vapor surrounding said electrodes, and heat insulating means to maintain the condition of said gas constant adjacent the smaller of said electrodes. 30

9. A television lamp comprising a pair of spaced apart electrodes one of which is larger than the other, a mixture of neon and mercury vapor surrounding said electrodes, and heat insulating means to maintain the condition of said gas constant adjacent the smaller of said electrodes.

10. A television lamp comprising a pair of spaced apart electrodes one of which is formed of wire mesh, an ionizable gas surrounding said 40 electrodes, and heat insulating means to protect said gas against variation of temperature adjacent the other of said electrodes.

, 11. A television lamp comprising a pair of spaced apart electrodes, one of which is formed 5 of wire mesh, an ionizable gas containing mercury vapor surrounding said electrodes, and heat insulating means to protect said gas adjacent the other of said electrodes against variation of temperature.

12. A television lamp comprising a pair of spaced apart electrodes one of which is formed of wire mesh, anionizable gas containing a metal vapor surrounding said electrodes, a restricted path between said electrodes, and heat insulat- 56 ing means to maintain constant the condition of the gas around the other of said electrodes.

13. A television lamp comprising an envelope, a cathode within said envelope comprised of a relatively large amount of wire mesh, an anode 60 within said envelope spaced apart from said cathode, an ionizable gas containing a metal vapor within said envelope, said envelope having a restricted path between said anode and cathode, and heat insulating means to prevent variation of temperature of, said gas in the neighborhood of said anode.

14. A television lamp comprising a cathode formed of along strip of Wire mesh rolled into a cylinder, an anode spaced from said cathode, an ionizable gas surrounding said anode and cathode and containing mercury vapor, and means to prevent variation of temperature of said gas adjacent said cathode.

15. A television lamp comprising an envelope,

said envelope consisting of a pair of spaced apart transparent bulbs connected by a transparent tube, a cathode in one of said bulbs, said cathode having a suriace-to-volume ratio of several hundred and having a surface area which is several hundred times the cross-sectional area of said tube, an anode in the other oi said bulbs, an ionizable gas within said bulbs and tube, and heat insulating means to prevent variation of temperature of the gas adjacent said anode.

16. A television lamp comprising a pair of spaced apart transparent bulbs, a small diameter tube connecting said bulbs, a cathode in one oi said bulbs, said cathode having a surface-tovolume ratio of several hundred and having a surface area which is several hundred times the cross-sectional area of said tube, an anode in the other of said bulbs, an ionizable gas within said bulbs and tube and containing a metal vapor, means to make electrical connection to said anode and cathode through the walls of said bulbs, means to prevent discharge from overheating the walls of said bulb where said connections are made, and means to prevent variation of temperature oi said gas adjacent said anode.

17. A discharge lamp comprising a pair of spaced electrodes, an envelope forming a greatly restricted, elongated, path between said electrodes, the surface area of at least one of said electrodes being several hundred times the cross-sectional area of said path and a gaseous conductive medium within said envelope including a small amount of a metal vapor.

18. A discharge lamp comprising a pair of spaced electrodes one of which is formed of a plurality of layers of wire mesh, an envelope forming a greatly restricted elongated path between said electrodes, said wire mesh electrode having a surface area several hundred times 40. greater than the cross-sectional area of said path and a gaseous medium containing mercury vapor within said envelope.

aoaaaoo 19. A discharge lamp comprising a pair of spaced apart bulbs connected by a relatively small diameter transparent tube, a cathode in one of said bulbs composed of a plurality of layers 01' wire mesh and having a cross section greater than the interior cross-section oi said tube, an anode in the other of saidbulbs and a fluid containing an ionizable gas and mercury vapor within said bulbs and tube. 1

20. A discharge lamp comprising two spaced apart bulbs connected by a relatively small diameter transparent tube, a cathode within one of said bulbs comprising a roll of wire mesh with a plurality of juxtaposed layers, the crosssectional diameter of said cathode being greater than the internal diameter of said tube, and a fluid within said bulb and tube containing an ionizahle gas and a metal vapor.

21. A discharge lamp comprising a pair of spaced electrodes one of said electrodes being composed oi! layers of wire mesh, a bulb around said last mentioned electrode, a restricted path leading from said bulb to said other electrode, and a fluid containing an ionizable gas and a metallic vapor surrounding said electrodes.

22. A television lamp for producing a modulated light comprising a pair of spaced apart transparent bulbs connected 'by a transparent tube having a diameter of approximately V4 inch, an anode in one of said bulbs, a cathode in the other of said bulbs, the bulb containing said cathode having a diameter of approximately 1% inches, said cathode comprising a strip of flne wire mesh approximately 1 inch wide and 9% inches long and loosely rolled into a cylinder of approximately inch diameter, connections for said anode and cathode sealed in the walls of said bulbs, and a filling of neon gas at a pressure of approximately 10 mm. of mercury within said bulbs and tube and including a drop of metallic mercury.

JOHN W. McKAY. 

